Play with just one finger. One stroke brain training addition puzzle game to improve your brain. A simple yet profound free brain training puzzle game using numbers. The rules are simple. Trace the numbers with your fingers, add them, make them 10 and erase them. Clear the stage by erasing all of them. Stage. There are 15,000 stages in total. Daily and weekly questions are available from a further 32,000 stages. Try to take advantage of the hints on difficult problems. However, hints cannot be used for weekly problems, so please consult with us on SNS before playing. Try these free brain training puzzle games, ranging from easy to difficult problems. Awards. Google Play Indie Games Festival 2019(Japan) Top 20